The present invention generally relates to extrusion of feed and food products. More specifically, the present invention relates to methods of extruding feed and food products that uses gelatin rather than starch as a binder during extrusion. The present invention also includes extruded feed and food products that contain gelatin as the binder and little, if any starch.
Extrusion cooking devices have long been used in the manufacture of a wide variety of edible and other products such as human food and animal feeds. For example, large extruders have been used for many years for the production of dry chunk-type dog foods. Generally speaking, such equipment includes an extruder having an elongated, tubular barrel with one or two elongated, helically flighted, axially rotatable screws therein. A multiple-orifice die is normally attached to the outlet end of the extruder barrel and is the prime means for shaping the extrudate.
In use, a material to be processed is passed into and through the extruder barrel and is subjected to increasing levels of temperature, pressure and shear. As the material emerges from the extruder die, it is fully cooked and shaped and may typically be subdivided using a rotating knife assembly. Conventional extruders of this type are shown in U.S. Pat. Nos. 4,763,569; 4,118,164 and 3,117,006.
Materials undergoing extrusion typically include a binder to improve internal cohesive strength so that the final product is less likely to fracture and create dust and wastage. Starch is a preferred binder for extruding food products since conditions during extrusion facilitate starch gelatinization that helps adhere each of the food components to one another in the final extruded product.
Unfortunately, quantities of starch are not always desired in food products, for many animals, such as gorillas, dogs, cats, horses, humans and the like. As a result, it is desired to produce a product containing virtually no starch.